How Could There Be Such a Disconnect Between the Science and Medical Practice?

“Most deaths in the United States are preventable and related to nutrition.” According to the most rigorous analysis of risk factors ever published, the Global Burden of Disease study, funded by the Bill and Melinda Gates Foundation, our diet is both the number-one cause of death and the number-one cause of disability in the United States, having bumped smoking tobacco down to number two. Smoking now kills about a half million Americans every year, whereas our diet kills thousands more.

If most death and disability is preventable and related to nutrition, then, certainly, nutrition is the number-one subject taught in medical school and the number-one topic your doctor talks with you about, right? How can there be such a disconnect between the science and the practice of medicine?

Let’s do a thought experiment. Imagine you’re a smoker in the 1950s. The average per-capita cigarette consumption was about 4,000 cigarettes a year. Think about that. In the 1950s, the average American smoked half a pack a day.

My video How Smoking in 1959 Is Like Eating in 2019 shows a series of 1950s tobacco ads featuring media stars, famous athletes, and even Santa Claus telling you to smoke. The message was clear: If you wanted to keep fit and stay slender, you made sure to smoke. Magazine ads also encouraged you to eat hot dogs to keep yourself trim, as well as lots of sugar to stay both slim and trim. One ad even claimed that sugar was less fattening than apples. Apples! Though one internal tobacco industry memo stated, “Apples connote goodness and freshness and we see many possibilities for our youth-oriented cigarette with this flavor.” They wanted to make apple-flavored cigarettes for kids. Shameless!

As those 1950s ads tell us, in addition to staying “fit,” staying “slender,” and “guard[ing] against throat-scratch”, “for digestion’s sake,” you could smoke. “No curative power is claimed for Philip Morris,” read one ad, “but—an ounce of prevention is worth a pound of cure.” Heeding that advice, it’s better to be safe than sorry, so you’d better smoke.

Like eating, smoking was a family affair. Marlboro ads featured babies with comment bubbles saying, “Gee, Mommy, you sure enjoy your Marlboro,” “You’re darn tootin my dad smokes Marlboro…he knows a good thing,” and “Just one question, Mom…can you afford not to smoke Marlboro?” In another ad from the 1950s featuring a stereotypically  nuclear family, the dad is given cartons of cigarettes from his doting children—one boy and one girl, of course—and even the dog has a carton as his doting wife looks on.

“Blow in her face and she’ll follow you anywhere” was one tobacco company’s tagline, and “No woman ever says no to Winchester” was another. After all, cigarettes are “so round, so firm, so fully packed.” After all, John Wayne smoked them…until he got lung cancer and died.

Back then, even the Flintstones were smoking, and so were the doctors. This is not to say there wasn’t controversy within the medical profession. Yes, some ads showed doctors smoking Camels, but, in others, physicians preferred Lucky Strikes, so there was some disagreement. Indeed, “eminent doctors…on high and impartial medical authority…call for Philip Morris.” Even “leading nose and throat specialists” couldn’t agree which cigarette is better for your throat. Probably best to stick to the science, and, touts another ad, “more scientists…smoke Kent…” This should not be rocket science—but even the rocket scientists had their favorite Viceroys for the “man who thinks for himself.”

Can you guess why the American Medical Association (AMA) “went on record as withholding endorsement of the Surgeon General’s Report on Smoking and Health, which documented the important role of cigarettes in…lung cancer”? A “gift from the tobacco companies” of ten million dollars may have had a little something to do with that. But why weren’t more individual doctors speaking out? There were a few gallant souls ahead of their time writing in to medical journals, as there are today, standing up against industries killing millions, but why not more? Maybe it’s because “the majority of physicians themselves smoke[d] cigarettes,” just like the majority of physicians today continue to eat foods that contribute to our epidemics of dietary diseases. What was the AMA’s rallying cry back then? Everything “in moderation.” The AMA said “[e]xtensive scientific studies have proved that smoking in moderation” is okay.

Eating the Standard American Diet today is like being a smoker in the 1950s. Just as smoking was rampant back then, think about what we’re feeding even hospital patients to this day.

We don’t have to wait until society catches up with the science. Sometimes it takes a whole generation for things to change in medicine. The old guard of smoking physicians and medical school professors die off, and a new generation takes its place—but how many people need to die in the interim?


I try to answer the question that arises in the minds of pretty much anyone dipping even  a single toe into the lifestyle medicine literature: “Wait a second. If this were true, why didn’t my doctor tell me?” If, for example, our number-one killer can be reversed through diet, why isn’t it front-page news and taught to every medical student, broadcast from every mountaintop by medical organizations, and featured in our government dietary guidelines? Still confused? Check out my other videos that address these questions:

For more on the parallels between smoking then and eating today, see:

Is the risk of smoking really comparable to following the Standard American Diet, though? See Animal Protein Compared to Cigarette Smoking and Will Cannabis Turn Into Big Tobacco?.

In health,
Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live, year-in-review presentations:

The Role of Pesticides in Parkinson’s Disease

In the original description of Parkinson’s disease by none other than Dr. James Parkinson himself, he described a characteristic feature of the disease: constipation, which may precede the diagnosis by many years. In fact, bowel movement frequency may be predictive. Men with less than one bowel movement a day were four times more like likely to develop Parkinson’s an average of 12 years later. This could be simply a really early symptom of the disease tied to decreased water intake, however. Many Parkinson’s patients report never really feeling very thirsty, and perhaps that led to the constipation. “Alternately, one may speculate that constipation also increases the risk of Parkinson’s disease as constipation results in a longer stay of the feces in the bowel and thus more absorption of neurotoxicants,” neurotoxins from the diet.

Two studies suggest an association between constipation and Parkinson’s, but, at the same time, 38 studies link the disease to pesticide exposure and by now more than 100 studies link pesticides to an increased risk of up to 80 percent.

Many of these studies are on occupational exposure, like that experienced by farmworkers, who may reduce their risk of Parkinson’s by wearing gloves and washing their clothes, but Parkinson’s has also been linked to ambient exposure. In the United States where approximately a billion pounds of pesticides are applied annually, just living or working in high-spray areas may increase Parkinson’s risk. It’s the same with using pesticides in the home. I didn’t realize how common household pesticide use was, and a study out of UCLA suggests it might not be such a good idea. 

Pesticides may cause DNA mutations that increase susceptibility for Parkinson’s or play a more direct role. Many neurodegenerative diseases appear to be caused by the buildup of misfolded proteins. In Alzheimer’s, it’s the protein amyloid beta; in Creutzfeldt-Jakob and mad cow disease, it’s prions; in Huntington’s, it’s a different protein; and in Parkinson’s disease, it’s a protein called alpha synuclein. A variety of pesticides—8 out of the 12 tested by researchers—were able to trigger synuclein accumulation in human nerve cells, at least in a petri dish, though the study has since been retracted so it’s unclear what the data actually showed.

The buildup of synuclein may play a role in killing off specialized nerve cells in the brain, 70 percent of which may be gone by the time the first symptoms arise. Pesticides are so good at killing these neurons that researchers use them to try to recreate Parkinson’s disease in animals. Is there any way to stop the process? As of this writing, there aren’t yet any drugs that can prevent this protein aggregation. What about flavonoid phytonutrients, natural compounds found in certain fruits and vegetables? Flavonoids can cross the blood-brain barrier and may have neuroprotective effects, so researchers tested 48 different plant compounds to see if any could stop the clumping of synuclein proteins into the little fibers that clog up the cell. And, indeed, they found a variety of flavonoids that can not only inhibit the spider web-like formation of synuclein fibers, but some could even break them up. It turns out flavonoids may actually bind to synuclein proteins and stabilize them.

In my video Berries vs. Pesticides in Parkinson’s Disease, you can see healthy nerve cells and the neurites, the arms they use to communicate to one another. After exposure to a pesticide, however, you can see how the cell is damaged and the arms are retracted. But, if you first incubate the nerve cells with a blueberry extract, the nerve cell appears better able to withstand the pesticide effects. So, this implies that flavonoids in our diet may be combating Parkinson’s disease as we speak, and healthy diets may be effective in preventing and even treating the disorder. However, these were all petri dish experiments in a laboratory. Is there any evidence that people eating berries are protected from Parkinson’s?

A study published quite a long time ago suggested the consumption of blueberries and strawberries was protective, but it was a tiny study and its results were not statistically significant. Nevertheless, that was the best we had…until now. In a more recent study, those eating a variety of phytonutrients were less likely to develop Parkinson’s disease. Specifically, higher intake of berries was associated with significantly lower risk. The accompanying editorial, “An Apple a Day to Prevent Parkinson Disease,” concluded that more research is necessary, but, until then, “an apple a day might be a good idea.” Of course, that’s coming from a man. Apples appeared protective against Parkinson’s for men, but not women. However, everyone appeared to benefit from the berries.

We may not want to have our berries with cream, though, as milk may be contaminated with the same kind of neurotoxic pesticide residues found in the brains of Parkinson’s disease victims.


I’ve produced other videos on Parkinson’s disease, including: 

Learn about other neurological muscular disorders, including essential tremor and ALS:

The same reason Parkinson’s may be related to constipation may also explain the breast cancer connection. For more on this, see my video Breast Cancer and Constipation.

What else can berries do?

But what about all the sugar in fruit? See my videos If Fructose Is Bad, What About Fruit? and How Much Fruit Is Too Much?.

In health,
Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live, year-in-review presentations:

How to Boost DNA Repair with Produce

“In the light of strikingly consistent observations from many epidemiological [population-based] studies, there can be little doubt that the habitual consumption of diets high in fruits and vegetables helps to reduce the risk of development of degenerative diseases, including many types of cancers.” Not satisfied with merely telling people to eat their fruits and veggies, scientists want to know the mechanism. I discuss this topic in my Which Fruits and Vegetables Boost DNA Repair? video.

Not just vehicles for antioxidants, fruits and vegetables contain innumerable phytonutrients that can boost our detoxification enzymes, modulate gene expression, and even modulate DNA repair pathways. “Until fairly recently…it was generally assumed that functions as important as DNA repair were unlikely to be readily affected by nutrition,” but, if you compare identical twins to fraternal twins, only about half to three quarters of DNA repair function is genetically determined. We may be able to control the rest.

“It is estimated that, on average, there are 800 incidents of DNA damage [in our bodies] per hour,” which is about 19,000 hits to our DNA every day. What’s more, “that DNA damage can cause mutations and give rise to cancer, if not repaired.” Thankfully, “the regulation of [DNA] repair can be added to the list of biological processes that are influenced by what we eat—and, specifically, that this might constitute part of the explanation for the cancer-preventive effects of many plant-based foods.”

Any plants in particular? Nine fruits and vegetables were tested to find out which ones were better able to boost DNA repair: lemons, persimmons, strawberries, oranges, choy sum (which is like skinny bok choy), broccoli, celery, lettuce, and apples. Which ones made the cut? Lemons, persimmons, strawberries, broccoli, celery, and apples all conferred DNA protection at very low doses.

Lemons, for example, were found to cut DNA damage by about a third. Was it the vitamin C? No. Removing the vitamin C from the lemon extract did not remove the protective effect. However, if you first boiled the lemon for 30 minutes, the protective effect was lost.


If it’s not the vitamin C, what might it be? That’s the subject of my video Citrus Peels and Cancer: Zest for Life?

Surprised that the lemon benefit was abolished by cooking? Find out which vegetables it may be best to eat raw in Best Cooking Method.

What about cooked versus raw garlic? See my video Inhibiting Platelet Activation with Garlic and Onions.

For more on DNA protection and repair, see:

In health,
Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live, year-in-review presentations: